1. Field of the Invention
The present invention relates to cooling a dry-running gas seal.
2. Description of the Related Art
Dry-running gas seals are a relatively mature technology. One of the initial working concepts of dry-running gas seals was provided in U.S. Pat. No. 3,499,653 to Gardner. Further refinements which have improved the performance of dry-running gas seals are disclosed, for example, in U.S. Pat. Nos. 4,212,475 to Sedy and 4,768,790 to Netzel et al.
Dry-running gas seals offer the advantage of consuming less power than older oil buffered gas seals. However, gas is a rather poor conductor of heat. Thus, although absolute levels of power generated are small, the temperature buildup in the seal cavity of dry-running gas seals can be great. For example, the 3-5 horsepower generated for a seal on a 4 inch shaft operating at 1,000 psig and 16,000 rpm can result in operating temperatures as high as 400.degree. F.
Increased temperature buildup causes reduced "O" ring life and increased differential thermal growth between the seal rings and their carriers.